The phrase lowest common denominator is a phrase that has a meaning opposite to its literal meaning. Are there any other phrases like that? What is the term used for such phrases?

Edit: Obviously, there are endlessly many such examples in the general class of irony; we're looking for phrases that are used in meanings opposite to their literal meaning, but with no hint of sarcasm or irony.

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@Mehper: Not quite… this is about phrases, not words. And unlike that question, it is about not about phrases which have two opposite meanings both in use, but about (non-sarcastic) phrases where usage in the literal sense is rare relative to the common usage in the opposite sense.
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ShreevatsaRJan 29 '11 at 17:58

2

Are there any other phrases like that? Fat chance!
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KosmonautJan 29 '11 at 18:27

As the author of the auto-antonyms question, I second what @ShreevatsaR says. This question here is quite different indeed.
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RegDwigнt♦Jan 29 '11 at 19:24

Some dictionaries support the common usage, and there is a postulate in military theory that holds that the chance that a unit will break (i.e. lose essentially all of its fighting effectiveness) becomes non-trivial around 10% casualties (though the actual threshold is a matter of morale, training, experience, and group psychology).
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dmckeeJan 31 '11 at 18:16

As far as I know, decimation was a punishment in in the Roman army: it is historically not directly related to losing men in battle.
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CerberusFeb 14 '11 at 16:29

Actually, it turns out the meaning of "decimate" as "reduce by 10%" (in general) is a spurious insertion into the dictionary, having never been used that way in English. See here.
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ShreevatsaRMar 14 '11 at 12:54

@ShreevatsaR: ok, so it only applies to Roman military unites. But it's still a 10% reduction :)
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Mr. Shiny and New 安宇Mar 14 '11 at 14:59

On the (rare) occasions when I use this phrase, I have taken to saying "as if I could care less".
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HellionJan 31 '11 at 17:48

@jbpjackson Both phrases are correct and acceptable usages. Although the phrases seem to be saying two opposite things, in fact they are the same: it's "I could afford to care less about this because I have no interest" vs. "I couldn't care less about this because I already have lost all interest".
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narxOct 8 '11 at 22:30

An opinion: "I could care less" means I care a little, but could care less, whereas "I couldn't care less" means I do not care.
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zespriMar 24 '14 at 1:55

I always found it counter-intuitive that semi is used to refer to tractor-trailers, which are usually the largest vehicles on roads. It makes sense though when you look at the evolution of the term: first there were regular trailers, then semi-trailers lacking front axles and the 18-wheeler trucks used these, and eventually the word "semi" described these enormous trucks.

Perhaps the easiest way for the literal meaning to be the opposite of the intended meaning is for the phrase to have the wrong number of negations. As I'd noticed while answering another question recently, this includes phrases like

There are a lot of words which may have originally been used ironically but have now totally changed their common meaning, such as "awful" which is literally synonomous with "awesome" but now almost exclusively means "very bad" whereas "awesome" means "very good".

A “random variable” (in Probability Theory) is itself not random, but rather a highly specific assignment (function) defined on the sample space.

“weight” is commonly accepted as a synonym for “mass”, but in fact they are distinct notions.

An object in “free fall” can actually be rising. (“Free fall” simply means that gravitation is the only force acting on the body (neglecting air resistance, of course). So, when you toss a ball upwards, it is in “free fall” from the moment it leaves your hand.)

An elevator (and escalator) gives you a ride downwards as well as upwards.

A private (in the military) is anything but.

The formula for compound interest does not give you the compound interest (but the entire future value of the investment).

Also, George Orwell’s novel “Animal Farm” contains many contradictory terms which, from the standpoint of the novel, are literal, not ironic.

In a press release during the American interdiction of Al Qaeda in Afghanistan, Rear Admiral John Stufflebeem was quoted as saying, in relation to a Taliban fighter who claimed to be an American citizen: “He is in control of US military forces”.

By inference from the context, it was apparent that what he really meant was “under the control of US military forces”

Well, thank heavens for that! is all I can say...

Another example: Hilary Clinton's use of 'underscore' to mean 'under-score' which can be confusing in the negative (from memory, something like ‘we can’t underscore the importance of this development in Pakistan” (APR 2009).

(Made worse by the use of "can't" where I think she really meant "shouldn't".)

In UK spoken English (and usually, it seems to me, in the US), the latter is differentiated from the former not just by a momentary interruption to the flow, but by putting the emphasis on 'score' rather than 'un'.